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The inference rules and control functions

<h2>Package Specification</h2>

The entry point of the package is <tt>RuleTables</tt>, which dispatch the premises 
(a task, and maybe also a belief) to various rules, according to their type combination.
<p>
There are four major groups of inference rules:
<ol>
    <li><tt>LocalRules</tt>, where the task and belief contains the same pair
    of terms, and the rules provide direct solutions to problems, revise beliefs, 
    and derive some conclusions;</li>
    <li><tt>SyllogisticRules</tt>, where the task and belief share one common term,
    and the rules derive conclusions between the other two terms;</li>
    <li><tt>CompositionalRules</tt>, where the rules derive conclusions by compose or
    decompose the terms in premises, so as to form new terms that are not in the two premises;</li>
    <li><tt>StructuralRules</tt>, where the task derives conclusions all by itself,
    while the other "premise" serves by indicating a certain syntactic structure in a compound term.</li>
</ol>
In the system, forward inference (the task is a Judgment) and backward inference 
(the task is a Question) are mostly isomorphic to each other, so that the 
inference rules produce clonclusions with the same content for different types of tasks. 
However, there are exceptions. For example, backward inference does not generate compound terms.
<p>
There are three files containing numerical functions:
<ol>
    <li><tt>TruthFunctions</tt>: the functions that calculate the truth value 
    of the derived judgments and the desire value (a variant of truth value) of the
    derived goals;</li>
    <li><tt>BudgetFunctions</tt>: the functions that calculate the budget value of
    the derived tasks, as well as adjust the budget value of the involved items 
    (concept, task, and links);</li>
    <li><tt>UtilityFunctions</tt>: the common basic functions used by the others.</li>
</ol>
In each case, there may be multiple applicable rules, which will be applied in parallel. 
For each rule, each conclusion is formed in three stages, to determine (1) the content 
(as a Term), (2) the truth-value, and (3) the budget-value, roughly in that order.
<p>
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